This project is directed at the investigation and development of an ultrasound method for quantitative assaying of the gelation of sickle cell hemoglobin in intact red cell and an optical method for assaying of sickling. These techniques can be used in research or clinical laboratories for assessing the effectiveness of various potential therapeutic agents. The ultrasound technique is based on the fact that ultrasound absorption in sickle cell blood and hemoglobin solution is related to the degree of deoxyhemoglobin S polymerization. The optical technique is proposed as a sickling assay because processes such as the erythrocyte sickling in which alterations in cell shape and/or size are involved may affect the optical properties of the cell as well. These methods are direct and independent of the subjective type of judgment required in microscopical examination. In addition, efforts will also be focused on the application of these two modalities to kinetic studies of intracellular gelation and sickling. These results can be used to determine the exact relationship between gelation and sickling. The ultrasonic data to be obtained will provide a better understanding of the interaction of ultrasound and micromolecular suspensions and suggest further applications.